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<!DOCTYPE html>
<html prefix="og: http://ogp.me/ns#">
<head>
<title>From Traces To (Formal) Models - William Durand</title>
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<meta property="og:title" content="From Traces To (Formal) Models - William Durand">
<meta property="og:description" content="">
<meta property="og:image" content="">
</head>
<body>
<div class="reveal">
<div class="slides">
<section>
<h1 class="title">From Traces To (Formal) Models</h1>
<em>William Durand - February 13, 2014</em>
</section>
<section>
<section data-markdown>
<script type="text/template">
## About Me
<br>
* PhD student at Michelin / LIMOS
* Graduated from IUT and ISIMA
* I <i class="icon-heart"></i> Open Source
<img src="images/clermontech.png" class="clermontech-badge" />
</script>
</section>
<section data-markdown>
<script type="text/template">
## PhD Topic
<br>
Automated **Test** Generation for applications and production machines in a
**Model-based Testing** approach.
</script>
</section>
</section>
<section data-markdown>
<script type="text/template">
## Agenda
<br>
* Introduction
* Model-based Testing
* Current Research
* Conclusion
</script>
</section>
<section>
<section data-markdown>
<script type="text/template">
## Software Testing
<p class="fragment">
<br>
**Software testing** is the process of **analyzing a software**
<br>item **to detect the differences between existing and
<br>required conditions** (that is, bugs) and to evaluate the
<br>features of the software item.
</p>
<p class="fragment">
<br>
It is a **Verification** and **Validation** process.
</p>
<p class="fragment">
<br>
**Validation** → "Are we building the right software?"
<br>
<br>
**Verification** → "Are we building the software right?"
</p>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Why?
<br>
<ul>
<li>To find **faults** (G. Myers, The Art of Software Testing)</li>
<br>
<li>To provide **confidence** of reliability, correctness,<br>and absence of particular faults</li>
</ul>
<br>
<br>
<i class="icon-warning-sign"></i> This does **not** mean that the software is completely
free of defects. Rather, it must be good enough for its intended use.
</script>
</section>
<section data-markdown>
<script type="text/template">
## How?
</script>
</section>
<section data-markdown>
<script type="text/template">
## Industry
<br>
**Unit** Testing, **Integration** Testing, **Functional** Testing, System Testing,
Stress Testing, Performance Testing, Usability Testing, Acceptance Testing,
Regression Testing, Beta Testing, <Whatever You Want> Testing
<br><br>
<p class="fragment left">
<i class="icon-thumbs-up"></i> People now understand the need for testing things
</p>
<p class="fragment left">
<i class="icon-thumbs-down"></i> They mostly do testing by hand...
</p>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Academia
<p class="fragment">
<br>
One approach is to...
<br>
</p>
</script>
</section>
</section>
<section>
<section data-markdown>
<script type="text/template">
## Model-based Testing
</script>
</section>
<section data-markdown>
<script type="text/template">
## Definition
<br>
**Model-based Testing** (MbT) is **application of Model-based design** for designing and
optionally also executing artifacts<br>**to perform software testing**.
<br>
**Models** can be used to represent the **desired behavior<br>of an SUT**, or to represent
**testing strategies** and a **test environement**.
<br>
<small>
<a href="http://en.wikipedia.org/wiki/Model-based_testing">http://en.wikipedia.org/wiki/Model-based_testing</a>
</small>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Why?
<br>
* To bring the benefits of automation to new parts of the test cycle
(test cases creation for instance)
* To provide testers more effective tools
* To reduce cost and cycle time
* To leverage formal methods
</script>
</section>
<section data-markdown>
<script type="text/template">
## Models
<br>
A **Model** is a description of a system that helps you understand and predict its behavior.
<br>
<br>
It does **not need to completely describe it** to be effective.
<br>
<br>
<p class="left">
**Behavior/Control oriented**: Finite Automata (FSM, LTS), Petri Nets,
Synchronous Languages (Lustre, Scade)
<br>
<br>
**Data oriented** (pre/post): JML, Spec#, OCL, B-Method, Praspel
</p>
</script>
</section>
<section data-markdown>
<script type="text/template">
## The Big Picture
</script>
</section>
<section data-markdown>
<script type="text/template">
## Three Stages
<br>
1. Formally modelling the requirements (specification);
2. Generating test cases from the model;
3. Running these test cases against an actual SUT and evaluating the results.
<br>
<i class="icon-info-sign"></i> Combining 2. and 3. leads to **On-The-Fly Testing**.
</script>
</section>
<section data-markdown>
<script type="text/template">
## Test Generation
<br>
* Based on Finite State Machines
* Based on Symbolic Transition Systems
* Based on Labelled Transition Systems
</script>
</section>
<section>
<h2>Labelled Transition Systems</h2>
<br>
<p class="float-left">
<img src="images/lts.png" />
</p>
<p class="float-right">
<br>
$$ L = (S, Act, \rightarrow) $$
<br>
with
<br>
$$ S = \lbrace s_{1}, s_{2}, s_{3}, s_{4} \rbrace $$
<br>
and
<br>
$$ Act = \lbrace COFFEE, TEA, BUTTON \rbrace $$
</p>
</section>
<section>
<h2>Traces</h2>
<p>
<br>
$$
\begin{align}
traces(s_{3}) =
& \lbrace \\
& BUTTON, \\
& BUTTON \cdot TEA \cdot BUTTON, \\
& \dots \rbrace = traces(s_{1}) = traces(s_{4}) \\
\\
traces(s_{2}) =
& \lbrace \\
& TEA, \\
& COFFEE, \\
& TEA \cdot BUTTON \cdot TEA, \\
& \dots \rbrace
\end{align}
$$
</p>
</section>
<section>
<h2>Input/Output LTS</h2>
<br>
<p class="float-left">
<img src="images/iolts.png" />
</p>
<p class="float-right">
<br>
<br>
<br>
$$
\begin{align}
Act_{I} = & \lbrace BUTTON?, COFFEE?, TEA? \rbrace \\
Act_{U} = & \lbrace COFFEE!, TEA! \rbrace
\end{align}
$$
</p>
</section>
<section data-markdown>
<script type="text/template">
## Automated Generation Of Specification Models
<br>
* By leveraging the API documentation
* By **instrumenting** the code (tracing)
* By leveraging the logs
* By **monitoring** the system
</script>
</section>
</section>
<section>
<section data-markdown>
<script type="text/template">
## Current Research
</script>
</section>
<section data-markdown>
<script type="text/template">
## Challenge
<br>
Based on a software, running in a<br>production environment, would it possible to:
<br>
<br>
1. extract a **knowledge base**
2. that can be formalized by a **model**
3. that can be used to **generate tests** and/or **specifications**?
</script>
</section>
<section>
<h2>Context (1/2)</h2>
<br>
<p>
Michelin relies on a method close to the <strong>C</strong>omputer <strong>I</strong>ntegrated <strong>M</strong>anufacturing
(CIM) approach to control its production:
</p>
<div class="float-left" style="width: 65%">
<ul style="margin-top: 5%">
<li>L4: Business Software</li>
<li>L3: Virtual level as it is not that used (Factory Management)</li>
<li><strong>L2: Supervision / Workshop Management</strong></li>
<li>L1: Automata</li>
</ul>
</div>
<div class="float-right" style="width: 60%">
<img src="images/levels.png" />
</div>
<p>These levels can exchange data among them.</p>
</section>
<section data-markdown>
<script type="text/template">
## Context (2/2)
<br>
Focus on **Level 2** applications but, then again,
<br>there are a lot of differences between them, such as:
* Programming Language
* Framework
* Design
* Version
</script>
</section>
<section data-markdown>
<script type="text/template">
## Hypotheses
<br>
1. Applications deployed in production behave as expected
2. Don't consider (existing) specifications
</script>
</section>
<section data-markdown>
<script type="text/template">
## The Big Picture
</script>
</section>
<section data-markdown>
<script type="text/template">
## Traces
<br>
A sequence of observable actions produced by an application.
<br>
**Raw** traces are collected from various sources,
including the **production environment** thanks to a
monitor.
<br>
<br>
<em>
<i class="icon-info-sign"></i> Traces in the context of web applications are HTTP requests and responses.
</em>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Domain Expert
<br>
A (human) domain expert can deduce the meaning of an application
execution by reading these **traces**.
<p class="fragment">
<br>
<i class="icon-lightbulb"></i> What about doing the same, **programmatically**?
</p>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Expert System
<br>
In Artificial Intelligence, an **expert system** is a computer system that
**emulates the decision-making ability of a human expert**.
<br>
<br>
Designed to **solve complex problems by reasoning about knowledge**, and **not** by
following the procedure of a developer as is the case in conventional programming.
<br>
<br>
<em>
<i class="icon-info-sign"></i> Java [JBoss Drools Expert](https://www.jboss.org/drools/drools-expert.html)
engine is a powerful expert system.
</em>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Rules
<br>
First-Order Predicate Calculus
IF condition
THEN
action
ENDIF
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 1 - Filtering
<br>
Cleans up the trace set given as input, removing **noise**,<br>a.k.a. **irrelevant** traces.
<br>
<br>
The resulting structured trace set is given to the next layer.
<br>
<br>
<em>
<i class="icon-info-sign"></i> In the context of web applications, HTTP requests/responses
related to assets (CSS files, JavaScript files, images) are meaningless.
</em>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 2 - IOSTS Transformation
<br>
Based on a the previous **structured trace set**, this layer performs a IOSTS transformation,
by **translating valued actions of a trace into IOSTS transitions**.
<br>
<br>
This first model is re-generated each time new traces are received, and then passed to the next layer.
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 2 - Example
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 2 - Minimisation
<br>
The previous IOSTS is reduced in term of location size by applying a bisimulation
minimisation technique.
<br>
<br>
GET("https://github.com/")
GET("https://github.com/login")
POST("https://github.com/session")
GET("https://github.com/")
GET("https://github.com/willdurand")
GET("https://github.com/willdurand/Geocoder")
POST("https://github.com/logout")
GET("https://github.com/")
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 3 to N - Abstraction
<br>
Composed of rules that emulate the ability of a human expert to **simplify transitions**,
to **analyze transition syntax** in order to deduce more meaningful information related to
the targeted application, and to **construct more abstract models**.
<br>
<br>
Each layer takes an **IOSTS given by the direct lower** one. It represents the current **base of facts**.
<br>
<br>
Layer 3 contains low level, generic rules that can be reused against different applications.
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 3 - Example
<br>
rule "Identify Login Page"
when
$t: Transition(
Action == GET,
Guard.response.content contains('login-form')
)
then
modify ($t) { Assign.add("isLoginPage := true") }
end
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 3 - Example
<br>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 4 - Example
</script>
</section>
<section data-markdown>
<script type="text/template">
## Layer 5 - Example
</script>
</section>
<section data-markdown>
<script type="text/template">
## Framework
</script>
</section>
<section data-markdown>
<script type="text/template">
## The Explorer
<br>
**The more traces, the better model in term of expressiveness.**
<br>
<br>
A **robot explorer** is used to **increase the amount of traces**<br>that are sent to the
model generator (i.e. the component that embeds the Expert System).
<br>
<br>
<i class="icon-warning-sign"></i> It can only be applied on event-driven applications.
</script>
</section>
<section data-markdown>
<script type="text/template">
## Strategies
<br>
Our **robot explorer** uses intelligent crawling guided by strategies, rather than blind
exploration.
<br>
<br>
Strategies are defined by **rules** that define how to find new states to visit. This is an
**orthogonal layer**.
<br>
<br>
<em>
<i class="icon-info-sign"></i> BFS and DFS are common strategies to explore a web application.
</em>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Recap'
</script>
</section>
<section data-markdown>
<script type="text/template">
## **Auto**matic **Funk**tional Testing Tool
<br>
Written in Java, PHP, Node.JS, and JavaScript.
<br>
Distributed system thanks to RabbitMQ.
<br>
Service Oriented Architecture FTW!
<br>
<em>
<i class="icon-warning-sign"></i> This tool has been built for web applications.
<br>Michelin will get its own internal tool.
</em>
</script>
</section>
<section data-markdown>
<script type="text/template">
## So, What?
<br>
The **final model** gathers useful information which allow to:
1. generate test cases;
2. detect potential issues;
3. perform security testing.
</script>
</section>
</section>
<section data-markdown>
<script type="text/template">
## Conclusion
<br>
<p style="text-align: left">
<i class="icon-smile"></i> Once rules are written, it is quite **easy to construct models**.
<br>
<i class="icon-frown"></i> However, rules tend to be **hard to write**, and to maintain.
</p>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Thank You.
### Questions?
<br><br>
<br><br>
<ul class="me">
<li>
<i class="icon-globe"></i> <a href="http://williamdurand.fr" title="website">williamdurand.fr</a>
</li>
<li>
<i class="icon-github"></i> <a href="https://github/willdurand" title="github">github.com/willdurand</a>
</li>
<li>
<i class="icon-twitter"></i> <a href="https://twitter.com/couac" title="twitter">twitter.com/couac</a>
</li>
</ul>
</script>
</section>
</div>
</div>
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